OK, so I tried to relate the equation P=Fv to the given equation that Pave^2= 3(Pftp^2)/Nh. I put Nh in terms of distance to satisfy the requirement that the answer should be in terms of Pftp and distance by saying Nh = distance/Vave. I also substituted Pave with Fvage.
(FVage)^2 =...